The first one to be tested unknowingly during Episode 5 of This is Infinite is the leader, Sunggyu.
After being woken up from his sleep, he was dropped at the Cine City/Horim Art Center Bus Stop in Gangnam. It's the bus station just beside CGV Cine City, a famous shopping and entertainment destination even among artists.

The Galleria

Sinsadong, Gangnam-gu, Seoul

(서울 강남구 신사동)

Dongwoon and Sungjong were dropped off in front of Galleria Mall in Chungdam-dong.

A lot of people know this place and I have posted several entries already with this as the location like for Shin's Family and Chen of EXO.

To get here, all you have to do is ride the Yellow Line Subway and get off the Apgujeong Rodeo Station EXIT 7. It's directly in front of the mall.

I have stated before that this is the nearest station to SM Entertainment's old building and is probably the most used for those who wish to go to the Korean entertainment companies.

Very useful, yes?

Apgujeong Station Exit 1

Apgujeong-dong, Gangnam-gu, Seoul

(서울 강남구 압구정동)

This is where Woohyun, Sungyeol and Hoya were dropped off.

I honestly kinda felt pity towards them because the ahjumma they called to recognize them just turned her back on them.

Hangang ParkGangnam-gu, Seoul
Judging by the course of their drop-off locations, I am guessing that this part of Hangang Park is located between Dongho and Hannam Bridges. :) I bet it's closer to Hannam since behind their bus is a basketball court which I think is where EXO played. HEH.
And this is where Myungsoo was dropped off, and instantly be recognized. HAHAHA
I bet the PDs brought L here to really test if he's really the face of the group and being the only one who was recognized, it has been proven that Infinite has a dangerous visual. :))))